Posttraumatic Stress Disorder (PTSD) continues to be a pressing public health challenge, not only among Vietnam combat veterans, but also among community residents who are victims of domestic violence, rape, physical assault, serious automotive accidents, and other severely traumatic events. This application is for a competing renewal of an ongoing longitudinal study of PTSD, as experienced by community residents of a major metropolitan area in the United States. Baseline data were gathered in 1989 in personal interviews with 1,007 young adults, who were 21 to 30 years of age. Follow-up interviews were conducted in 1992 and 1994 with more than 97 percent of the sample. This application is for the continuation of the research on PTSD in this well characterized epidemiologic sample. During the continuation, the research team will bring together previously separate lines of research on PTSD: epidemiologic research in the general community and neurobiologic research on sleep and stress hormone abnormalities, previously conducted with specialized samples, primarily Vietnam veterans. Previous findings from these lines of research emphasize the role of preexisting vulnerabilities in PTSD and the distinctive pathological processes in the disorder and its maintenance. The investigators propose to conduct an additional assessment of the sample, when the subjects are 35 to 39 years of age. A clinical assessment of PTSD is proposed, using a two-stage design. Subsets of subjects with PTSD, exposed to traumatic events but with no PTSD, and not exposed, will be recruited for sleep studies and studies of hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) activation. Hypotheses about the epidemiology of traumatic events and PTSD will be tested (e.g., prospective risk factors for PTSD sensitization by prior exposure, period of risk for PTSD, risk for abuse of prescribed drugs following PTSD). Hypotheses about sleep concern sleep disturbance (e.g., sleep induction, continuity) and REM function (e.g., REM density). Hypotheses about neuroendocrine function concern alterations in 24 hour urinary-free cortisol and norepinephrine sections associated with PTSD.